The invention set forth in this specification relates to new and improved breathing apparatuses. A breathing apparatus in accordance with this invention is especially constructed for use with and is primarily intended for use in administering oxygen to a patient. It is, however, considered that breathing apparatuses in accordance with this invention can be employed for other purposes such as, for example, in supplying a breathable gas mixture to an individual in a location where the ambient air or gas is not breathable or to an individual engaged in scuba or underwater type activities or to an individual at an elevated altitude.
It is a matter of common knowledge that many different types of breathing apparatuses have been developed and utilized in the past. It is considered that those breathing apparatuses which have been primarily developed for and/or used in administering oxygen to a patient have been relatively undesirable because in effect they tend to "waste" oxygen in the sense that substantially all of the oxygen supplied to a patient through such an apparatus is not effectively delivered to the respiratory tract of the patient.
This is considered to be quite important in connection with the treatment of many patients because of the relative cost of oxygen. It has been recognized that if the oxygen used in treating patients could be more effectively utilized that many individuals would be better able to afford needed oxygen treatment. Common prior apparatuses for oxygen therapy have been constructed so that during a part of the breathing cycle of a patient some oxygen would escape to the ambient air.
It is recognized that various different types of breathing apparatuses known as "rebreathers" have been developed and utilized. In theory such "rebreathers" are advantageous inasmuch as they minimize the escape of breathable gas to the ambient surroundings. Many of such "rebreathers" have been utilized in connection with scuba or underwater type activities. While prior "rebreather" type breathing apparatuses are considered to be reasonably utilitarian in character it is also considered that such apparatuses in general tend to be unnecessarily complex and expensive. It is considered that the utilization of such prior "rebreathing" type apparatuses tends to be limited to a degree by what may be loosely referred to as reliability type problems. In the field of breathing apparatuses for use in oxygen therapy reliability is, of course, quite important. Further, the cost of the apparatus is also significant in making such therapy reasonably available.